Call billing and measurement methods for redirected calls

ABSTRACT

A call processing and billing method where the two billing records generated for a redirected call are transmitted to the same billing center or to the same network of interconnected billing centers, and where the two billing records are correlated to generate a single billing record for use in billing the call. The method is extensible for calls that are redirected more than once.

This application is a continuation of application Ser. No. 07/995,655,filed on Dec. 21, 1992 now abandoned.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following applications, which areassigned to the same assignee and filed of even data:

S. L. Greenspan, U.S. Ser. No. 07/994,556 "Call Transfer with AutomaticReturn", and

M. A. Burd et al., U.S. Ser. No. 07/993,754 now U.S. Pat. No. 5,432,845"Recurrent Call Prompter and Post Answer Call Redirection".

1. Technical Field

This invention relates to telecommuncations.

2. Background of the Invention

As stored program controlled switching systems have evolved, a widevariety of useful features have been developed to extend thecommunication capabilities such systems provide. One class of featuresrelates to redirecting calls. Refer to FIG. 33 and consider an examplewhere a customer at a calling station (1stStation) calls a businessusing an 800 number and the call is answered at a general customerrepresentative's station (2nd station). The representative and thecustomer talk for a few minutes and the representative determines thatthe customer should talk to a specialist employed by the same businessbut located in another city. The representative then transfers the callto the specialist's station (3rdStation) and disconnects from the call.Assume that the three stations are served by three different switches110, 120, 130. In present day practice, switch 110 serving thecustomer's station (1stStation) generates a first billing record inbilling subsystem 141 which includes both the time that the customer andrepresentative talk as well as the time that the customer and thespecialist talk (FIG. 37). Switch 120 serving the representative'sstation (2nd station) generates a second billing record in billingsubsystem 142 which includes the time that the customer and thespecialist talk (FIG. 37). Assume, for example, that switches 110 and120 are connected to billing centers 161 and 162 respectively. The firstand second billing records are transmitted to billing centers 161 and162, respectively, and two separate bills are generated. The first billmay be for twelve minutes and the second bill for ten minutes, a totalof 22 minutes, even though the caller was only talking for twelveminutes. This arrangement provides no flexibility in billing callsinvolving call redirection.

SOLUTION

This problem is solved and a technical advance is achieved in accordancewith the principles of the invention in an illustrative method where thetwo billing records generated for a redirected call are transmitted tothe same billing center or to the same network of interconnected billingcenters, and where the two billing records are advantageously correlatedto generate a single billing record for use in billing the call. In theabove examplary call scenario, a single bill for twelve minutes may begenerated. The method is extensible for calls that are redirected morethan once. The single bill may alternatively reflect other discountingplans. In an alternative method referred to and described herein asService 4, call history information is transferred and updated to followa call as it is redirected. The updated information is used in billingthe redirected call, providing measurements concerning the redirectedcall, and in controlling the call, for example when the call issubsequently returned to the station that initiated a transfer. Thealternative method is also extensible for calls that are redirected morethan once.

A call processing and billing method in accordance with the inventionincludes connecting a call from a first station to a second station.Contemporaneously with connecting the call to the second station, afirst billing record for the call is initiated. The call is thenconnected to a third station. Contemporaneously with connecting the callto the third station, a second billing record for the call is initiated.The first and second billing records are completed proximate to the endof the call. After the billing records are completed, they arecorrelated to generate a single billing record for use in billing thecall.

The invention is used in an illustrative service described herein andreferred to as Service 5. The invention is also used in threeillustrative services described herein and referred to as Services 1, 2,and 3, each of which also involves a switch having a new,transfer-with-automatic-return feature.

The connection of the call to the third station may involve conferencingthe third station into the call, or transferring the call to the thirdstation. A call transfer is effected in one of three ways: blindtransfer, consultation, or conference. With blind transfer, one of thefirst and second stations is not connected to the third station for aninitial two-way consultation before the other of the first and secondstations is connected to the third station. With consultation, the onestation and the third station are connected for an initial two-wayconsultation and thereafter the other station and the third station areconnected. With conference, the one station, the other station, and thethird station are initially connected for a conference and the onestation subsequently drops out.

Illustratively, the correlation comprises modifying one of the billingrecords based on the other. Alternatively, information from the twobilling records is in some fashion combined to generate a single billingrecord. Further, the two billing records may be compared and only one ofthem used, either unaltered or with some modification, as the singlebilling record. An identifier, e.g., a flag or other identifier, isincluded in either one or both of the first and second billing recordsfor use in the correlation. Rather than having a billing center performthe correlation, the two billing records may be correlated by aswitching system, e.g., a system serving one of the stations involved inthe redirected call.

As a further example, the first bill may be completed proximate to thecall redirection.

A further alternative method used in the arrangement of FIG. 40 includesconnecting a call from a first station to a second station.Contemporaneously with connecting the call to the second station, thetransmission of first call segment event messages is initiated to abilling center, e.g., a nationwide billing center. The call is thenconnected to a third station. Contemporaneously with connecting the callto the third station, the transmission of second call segment eventmessages is iniatiated to the same billing center. After all of thefirst and second call segment event messages have been transmitted, thebilling center correlates them to generate a single billing record foruse in billing the call.

DRAWING DESCRIPTION

FIG. 1 is a hardware diagram for an arrangement where Service 1described herein is implemented;

FIG. 2 is a call flow diagram for Service 1;

FIGS. 3-11 are action-event diagrams for a number of states used toimplement the call flow for Service 1;

FIGS. 12 is a state diagram summarizing transitions between the statesof FIGS. 3-11;

FIG. 13 is a hardware diagram for an arrangement where Service 2described herein is implemented;

FIG. 14 is a call flow diagram for Service 2;

FIG. 15 is a hardware diagram for an arrangement where Service 3described herein is implemented;

FIG. 16 is a call flow diagram for Service 3;

FIG. 17 is a hardware diagram for an arrangement where Services 4 and 5described herein are implemented;

FIG. 18 is a call flow diagram for Service 4;

FIG. 19 is a state diagram summarizing transitions between a number ofstates used to implement the call flow for Service 4;

FIGS. 20-27 are action-event diagrams for each of the states of FIG. 19;

FIG. 28 is a call flow diagram for Service 5;

FIG. 29 is a state diagram for Service 5 for an example referred toherein as Scenario A;

FIG. 30 is an event timing diagram for Scenario A;

FIG. 31 is a state diagram for Service 5 for an example referred toherein as Scenario B;

FIG. 32 in an event timing diagram for Scenario B;

FIG. 33 is a hardware diagram for an arrangement that implements a priorart billing service;

FIG. 34 is a state diagram summarizing transitions between a number ofstates used to implement the prior art service;

FIG. 35 is a call flow diagram for the prior art service;

FIGS. 36-37 are event timing diagrams for Scenario A with the prior artservice;

FIG. 38 is an event timing diagram for Scenario B with the prior artservice;

FIG. 39 is a hardware diagram of a host switching system and a switchadjunct, e.g., a service circuit node described herein; and

FIG. 40 is a hardware diagram for an arrangement that implements a new,alternative billing method.

DETAILED DESCRIPTION Terminology

The terms, 1stStation, 2ndStation, and 3rdStation are used herein torefer to stations of a calling party, called (and transferring) party,and transferred-to party, respectively. The 1stStation originates a callto a 2ndStation, which in turn transfers the call to a 3rdStation,establishing a talking path between the 1stStation and the 3rdStation.The services described herein also apply to cases where a 1stStationoriginates a call to a 2ndStation, the 1stStation transfers the call toa 3rdStation, establishing a talking path between the 2ndStation and the3rdStation. The transferring station is also referred to as one of thefirst and second stations while the non-transferring station is referredto as the other of the first and second stations.

The terms 1stStation, 2ndStation, and 3rdStation should be read broadlyas referring to customer and network equipment, telephones, computers,PBXs, and network and third-party switch adjuncts.

Services

The following description relates to five new telephone services:

Service 1: Attendant Service with Transfer-with-Return

In this service description, transfer-with-return and call-historyfeatures are illustrated in the context of a service center, in whichcustomers (1stStations) call an attendant (2ndStations), who in turn cantransfer the call to service specialists (3rdStations). Upon somedesignated signal (e.g., a flash, DTMF, or disconnect from the1stStation or 3rdStation) the 1stStation and/or 3rdStation arereconnected to the 2ndStation.

Service 2: SCN use of Transfer-with-Return feature so that SCN can beinformation gateway

In this service description, the notion of an attendant (2ndStation) isgeneralized to include switching adjuncts, in this case, a ServiceCircuit Node (SCN) that can invoke the transfer-with-return andcall-history features on a host switch. In such a case, the SCN is ableto establish independent call legs from or to a 1stStation and a3rdStation (the SCN acts as the 2ndStation), to apply a variety ofservice circuits (e.g., announcements, facsimile, and conferencefacilities), and to transfer the two call legs back to the host switch,so that the SCN is no longer pan of the talking path between the1stStation and 2ndStation. Upon some designated signal (e.g., a flash,DTMF, or disconnect from the 1stStation or 3rdStation) the 1stStationand/or 3rdStation are reconnected to the 2ndStation as a conference of1st, 2nd, and 3rdStations or two call paths--a communication pathbetween the 1st and 2ndStations and an independent communication pathbetween the 2nd and 3rdStations.

Service 3: ESM use of Transfer-with-Return feature so that ESM can beinformation & service circuit gateway

In this service, a service circuit node (SCN) is generalized to lesspowerful service adjuncts or CPE, e.g., automated telecommunicationssystems referred to herein as external service modules (ESMs).

Service 4: Service gateway without switch-based transfer-with-returncapability

In this service, a transfer-with-return sequence (1stStation calls2ndStation that transfers call to 3rdStation that, in turn, transferscall back to 2ndStation) is accomplished without thetransfer-with-return feature. Call history information is transferredand updated (either by the stations or the associated switches) as thecall is successively transferred. The information is usable in billingthe call, generating measurements for the call, and/or controlling thecall.

Service 5: Correlated billing records for call transfer sequences

In this service, a first billing record is initiated when a call isconnected from a 1stStation to a 2ndStation. A second billing record isinitiated when the call is connected to a 3rdStation. The first andsecond billing records are completed before or proximate to the end ofthe call and are transmitted to a billing center or network ofinterconnected billing centers where they are correlated to generate asingle billing record for billing the call.

Service 1: Attendant Service with Transfer-with-Return

These features are used by a group of 2ndStations (e.g., a group ofservice attendants) to transfer calls to service agents who specializein a particular area, and to then have the call transferred back to themfor service follow-ups, quality audits, etc. Four sets of features areidentified:

transfer-with-return feature

return transfer triggers, in particular a call termination trigger

call-history feature

call-termination notification

Feature Descriptions:

A) Transfer with Return

This feature allows a subscribing attendant (a 2ndStation) to transfer acall (from a 1stStation) to a 3rdStation, allowing a talking pathbetween the 1st and 3rd Stations and allowing the 2ndStation todisconnect from the call. However, following the disconnection by the2ndStation, the 1stStation and 3rdStation are reconnected to the2ndStation, if the 1st or 3rdStation signals appropriately; or the1stStation or 3rdStation are reconnected to the 2ndStation, if the3rdStation or 1stStation disconnects.

The feature works as a line-subscribed feature, that can be invoked on aper-call basis or automatically invoked on all calls. If subscribed toon a per-call basis, the attendant (2ndStation) may signal transfer withno return, transfer with return, or other subscribed to attendantfeatures, e.g., conference, hold, etc. If the attendant is part of amulti-line hunt or ACD group, the return-transfer is made to theattendant that initially handled the call. If the attendant is busy, thecall is forwarded to an appropriate co-worker.

B) Return Transfer Triggers

Reconnection to the 2ndStation is triggered in several ways:disconnection by the 1st or 3rd Station, and signaling (e.g., flash orDTMF) by the 1st or 3rdStation. If the feature allows the 1stStations or3rdStations to signal (e.g., flash or DTMF) reconnection to theattendant, then the transfer-with-return feature works in conjunctionwith 3-way calling. The 2ndStation could drop out of the conference andthen be asked to come back into the conference. In some cases, a3rdStation may be an automated service module, e.g., a mail system. Topermit the 1stStation to signal a return to the 2ndStation whiledisconnecting the 3rdStation, a call-termination trigger is needed.

C) Call-History Feature on Returned Transfer

So that the 2ndStation (the service attendant) knows that the call is apreviously handled call, and so that the 2ndStation is able to quicklyidentify which call is being returned, the transfer-with-return featureprovides call-history and call identification information in thecall-setup message. It also provides a reason message that specifies thereason for the return, e.g., 3rdStation disconnected, 1stStationrequest, etc.

D) Call-Termination Notification

In some call scenarios, both the 1st and 3rd Stations might disconnectbefore either is reconnected to the 2ndStation. In such cases, the2ndStation (the service attendant) might still be interested in the callhistory between the 1st and 3rd Stations. Thus, the feature permits theattendant to specify (perhaps during service subscription) whether ornot they should be notified if the caller and the called party both dropthe call.

Note that in the call flow of FIG. 2, the 2ndStation(the attendant)places the 1stStation (the caller) on hold; originates a call to a3rdStation (e.g., a service agent); conferences together the threestations; and finally disconnects the 2ndStation, leaving a talking pathbetween the 1st and 3rd Stations. The service concept also applies toother call flows. In particular, the 2ndStation could disconnect as soonas the call to the 3rdStation is set up but not answered, thus leavingthe 1st and 3rdStations in a tinging state. Further, the 2ndStationcould connect to the 3rdStation for two-way consultation prior toconnecting the 1stStation and 3rdStation.

FIG. 1 is a diagram of an exemplary network configuration. The1stStation, 2ndStation and 3rdStation are connected to switches 10, 20,and 30, respectively. Switches 10 and 20 and switches 20 and 30 areinterconnected by trunks 15 and 25, respectively, which may includeintermediate switches. Billing center 40 and billing subsystems 41, 42,and 43 are discussed later herein with respect to Service 5.

FIGS. 3-11 provide a state chart of how the call-with-return andcall-history features operate within switching system 20 for Service 1.FIG. 12 provides a summary of the state transitions.

To improve readability, the following descriptions are partitioned bystate. The notation for each state title should be read as: serviceconcept number-state number, state name, e.g., 1-1. state Initial,indicates that Initial is the name of the first state in the state modeldescribing service 1.

1-1. State Initial (FIG. 3)

The call flow begins in the state Initial, with the initial event,Incoming₋₋ call. This initial event initiates call processing.

The first action taken in this state is to translate the digits dialedby the 1stStation (i.e., the caller) into a specific directory number,and to then initiate a call-setup to the 2ndStation represented by thedialed directory number.

If the call to the 2ndStation is answered (i.e., an event answered isreceived from the 2ndStation), then connect 1st and 2nd Stations andtransition the state model to another state, 2way.

If the event disconnect is received from either station, then the callends.

1-2. State 2way (FIG. 4)

If the event disconnect is received from either station, then the callends.

If the 2ndStation sends an appropriate signal (e.g., a flash or DTMF),and the 2ndStation is a subscriber to the transfer-with-return feature,then place the 1stStation on hold, and transition the state model toanother state, 2way₋₋ 2ndStationActive.

1-3. State 2way 2ndStationActive (FIG. 5)

The 1stStation (caller) is on hold.

Several events are possible in this state:

event Initial Event

The state begins by processing the internally generated event, Initial₋₋Event. Processing this event results in a tone!collect₋₋ digits actionthat delivers a stuttered tone to the 2ndStation. The stuttered toneprompts the 2ndStation for a feature code, one of which istransfer-with-return, another is transfer-without-return (i.e.,call-transfer as it is currently done).

event collected digits

The digits signaled by the 2ndStation are received as the eventcollected₋₋ digits. If the collected digits indicate a request fortransfer-with-return, a Return₋₋ active indicator is set to true. If thetransfer-with-return or -without-return feature is requested, then asecond tone!collect₋₋ digits action delivers dial tone to the2ndStation. The dial tone prompts the 2ndStation for a directory number.If a valid directory number is received from the 2ndStation, acall-setup procedure is invoked and the state model then transitions toa new state, 3way₋₋ 2ndStationActive₋₋ 3rdStationSetUp

event signal

If the appropriate signal (e.g., a flash) is received by the switch fromthe 2ndStation, the call is returned to the previous 2-way talking pathbetween the 1stStation and 2ndStation, and state model transitions backto the state 2way.

NOTE: the feature may be implemented so that indicating a request forstarting transfer procedures is implied by the 2ndStations's (i.e., thesubscriber's) initial feature request (flash or DTMF). In this case,call flow would proceed directly from points (1) to (2) in FIG. 5.

1-4. State 3way 2ndStationActive 3rdStationSetUp (FIG. 6)

The 1stStation is on hold, and the 2ndStation has initiated transferprocedures. Several events are possible in this state:

event call failed

The call could not be connected to the designated directory number,perhaps because the 3rdStation was busy or did not answer. In thisevent, busy or ringing (as appropriate) is delivered to the 2ndStation.The state model then transitions to state 2way₋₋ 2ndStationActive.

event call answered

The 3rdStation answers the call. In this case, the switch establishes a2-way path between the 2nd and 3rd stations. The state model thentransitions to an new state, 3way₋₋ 2ndStationActive₋₋ 3rdStationActive.

event disconnect received from 2ndStation

The 2ndStation disconnects. In this event, the switch establishes a2-way connection between the 1stStation and the 3rdStation. Since the3rdStation has not yet answered, the 1stStation receives audibletinging. The state model then transitions to an new state, 2way₋₋1stStationActive₋₋ 3rdStationActive.

event signal received from 2ndStation

The 2ndStation (the subscriber) signals (typically, but not necessarily,by flashing) a request to return to the 2-way call with the 1stStation.In this event, a talking path is established between the 1st and 2ndstations, and the state model transitions back to the state 2way.

In the next two states, the 2ndStation has a two-way conversation witheither the 1stStation or the 3rdStation. The 2ndStation's signal (flashor DTMF) acts a toggle between these two states. If the 2ndStationsignals a conference request, procedures for a 3-way conversation areinitiated.

1-5. State 3way 2ndStationActive 3rdStationActive (FIG. 7)

In this state the 1stStation is on hold, while the 2nd and 3rd Stationsare connected in a talking path. Two events are significant in thisstate:

event signal for toggle received from 2ndStation

If the 2ndStation signals a single flash (or some DTMF equivalent) thenthe switch opens the path between the 2nd and 3rd Stations, and connectsa path between the 1st and 2nd Stations. The state model thentransitions to a new state 3way₋₋ 1stStationActive₋₋ 2ndStationActive.

event signal for conference received from 2ndStation

If the 2ndStation signals a double-flash (or some DTMF equivalent) thenthe switch creates a 3-way call between the 1st, 2nd, and 3rd Stations.The state model then transitions to a new state 3way.

1-6. state 3way 1stStationActive 2ndStationActive (FIG. 8)

In this state the 3rdStation is on hold, while the 1st and 2nd Stationsare connected in a talking path. Two events are significant in thisstate:

event signal for toggle received from 2ndStation

If the 2ndStation signals a single flash (or some DTMF equivalent) thenthe switch opens the path between the 1st and 2nd Stations, and connectsa path between the 2nd and 3rd Stations. The state model thentransitions back to the state 3way₋₋ 2ndStationActive₋₋3rdStationActive.

event signal for conference received from 2ndStation

If the 2ndStation signals a double-flash (or some DTMF equivalent) thenthe switch creates a 3-way call between the 1st, 2nd, and 3rd Stations.The state model then transitions to a new state 3way.

1-7. State 3way (FIG. 9)

In the 3way state, all three stations are connected together in a 3-wayconference.

If the 2ndStation disconnects, a 2-way call is created between the1stStation and the 3rdStation and the state model transitions to state2way₋₋ 1stStationActive₋₋ 3rdStationActive.

If the 1stStation or 3rdStation disconnects, a 2way call is createdbetween the two remaining stations (between the 2ndStation and3rdStation, or between the 1stStation and 2ndStation, respectively). If3rdStation disconnects, the state model transitions back to state 2way.If the 1stStation disconnects, the state model transitions to the state2way, but consider the 3rdStation as if it were the 1stStation (theoriginal 1stStation is no longer part of the call), except of course,the 2ndStation is now the call originator.

Not shown are procedures that allow the 2ndStation (the subscriber whoestablished the 3-way conference) to request the switch to create a2-way call between the 2ndStation and 1stStation (or between the2ndStation and 3rdStation), while placing the 3rdStation (or 1stStation)on hold.

1-8. State 2way 1stStationActive 3rdStationActive (FIG. 10)

In this state, the 2ndStation is not part of the call.

Initially, the connection between the 1st and 3rd station is either in aringing state or in a talking state (depending upon whether or not the2ndStation disconnected before or after the 3rdStation answered; or interms of the state model, depending on whether the previous state was3way₋₋ 2ndStationActive₋₋ 3rdStationSetUp or 3way).

Five events are significant:

event no answer received from 3rdStation

If the 3rdStation does not answer, the 1stStation continues to heartinging until the 1stStation signals a request to return the call to the2ndStation, or the 1stStation disconnects. No state transition isrequired.

event answer received from 3rdStation

If the 3rdStation answers, then the switch establishes a talking pathbetween the 1stStation and 3rdStation. No state transition is required.

event signal for return to 2ndStation received from 1stStation

The 3rdStation is released (disconnected) from call. If thetransfer-with-return feature is active, then the state model transitionsto the Return Call state; if the feature is not active, then the call isterminated and the 1st station is disconnected.

event signal for return to 2ndStation received from 3rdStation

If the transfer-with-return feature is active, then the state modeltransitions to the Return₋₋ Call state; if the feature is not active,then the call is terminated and the 3rd station is disconnected.

event disconnect received from 1stStation or 3rdStation

If the transfer-with-return feature is active, then the state modeltransitions to the Return₋₋ Call state; if the feature is not active,then the call is terminated and the remaining stations are disconnected.

1-9. State Return Call (FIG. 11)

Prior to this state, the 1st or 3rd Station disconnected or signalled arequest to reconnect a talking path to the 2ndStation (the serviceattendant and subscriber in Service 1). In this state, the 2ndStation issent an information message detailing call history information. Thisinformation allows the 2ndStation to separate new calls from returncalls, to construct service bills if appropriate, or to send billinginformation back to the host switch.

If the 1st or 3rd Station has disconnected and the 2ndStation answers,the state model transitions back to the state 2way and a two-way talkingpath is established between the 2ndStation and the remaining station.

If neither the 1st or 3rd Station has disconnected and the 2ndStationanswers, the call to the 2ndStation results in a 3-way call involvingthe 1st, 2nd, and 3rd Stations and a state model transition to the state3way.

Please note, the 1stStation can force a disconnect of the 3rdStation bysending the appropriate signal, e.g., a designated DTMF sequence.

Service 2: SCN use of Transfer-with-Return feature so that SCN can beinformation gateway (FIG. 13)

The features detailed in Service 2 are the same as those specified forService 1:

transfer-with-return feature

return transfer triggers, in particular a call-termination trigger

call-history feature

call-termination notification

In Service 1, these features were demonstrated with a human at eachstation. In contrast, in Service 2, the human attendant at the2ndStation is replaced with a Service Circuit Node (SCN).

An arrangement comprising an ISDN switching system 300, a servicecircuit node 400, and a database 500 is shown in FIG. 39. ISDN switchingsystem 300 is of the type disclosed in U.S. Pat. No. 4,592,048 issued toM. W. Beckner et al. on May 27, 1986. Service node 400 is of the typedisclosed in the AT&T A-I-Net™ Service Circuit Node (SCN) SystemDescription and the AT&T A-I-Net™ Service Circuit Node (SCN) ProductTechnical Specifications Release 1, both of Apr. 15, 1992. System 300comprises a control arrangement 310, a switching network 320, and lineunits 330 and is connected to analog station sets 211,212, and 213 aswell as other station sets not shown. System 300 is also connected toservice node 400 by a number of ISDN basic rate interface (BRI) lines.Service node 400 comprises a control computer 440, a switch fabric 420,and service circuits 430. Service circuits 430 provide the followingcapabilities: 1) digit collection, 2) tone detection/generation, 3) FAXreceipt, storage, and transmittal, 4) voice recording, storage, andplayback, 5) text-to-speech (TTS) announcements, 6) call setup throughthe switch fabric 420, 7) conference bridging, 8) transferring a call toa second party, and 9) returning call control to system 300. Database500 provides a reverse white pages directory which returns a callingparty name when a calling party number is provided. Although not shownin FIG. 39, service node 200 may be connected to a plurality of ISDNswitching systems in addition to system 100. System 300 with thetransfer-with-return and call history features added, together with SCN400 are used as switch 20 and the 2ndStation in FIG. 13.

The features illustrated in the call flow of HG. 14 can be used by theSCN (the 2ndStation in these examples) to transfer calls back to a hostswitch (thus increasing service reliability and decreasing trafficcapacity), and then regain call control when the 1 stStation or2ndStation disconnects (or appropriately signals). These features alsoallow the SCN to act as an information gateway to a variety of externalservice modules which are independent and which have no knowledge of theSCN.

This permits several extensions to the basic call flow describedearlier:

1. The call could be an in-band or out-of-band data call. This allowsthe concept to support both voice and data applications.

2. Because many automated systems can operate on multiple concurrentcalls, the call flow described previously can be broadened so that thecaller (the 1stStation) need not be placed on hold during theconversation between the 2ndStation (in this case, a SCN) and the3rdStation (i.e., service agent or ESM). Instead the SCN could maintainparallel conversations with the 1stStation and the 3rdStation beforeestablishing a talking path between the 1st and 3rd Stations. When the1st or 3rdStation requests reconnection to the 2ndStation (i.e. the SCN)the reconnection could either be a conference including all threeparties or two separate calls (1stStation to SCN, and SCN to3rdStation). This option for reconnection may be provisioned atsubscription time. In the case of the SCN, the service is provisioned tosupport reconnection as separate calls, because the SCN could apply itsown conference circuits if necessary.

3. Because a SCN is used as the automated attendant, the interactionsbetween caller and SCN could allow services in which the SCN:

plays voice or text-to-speech announcements (e.g., service options);

collects information that influences service behavior. For example,information might be collected via,

dtmf digit reception,

speech recognition,

speaker verification,

out-of-band signals from another switching center.

collects information for storage and subsequent analysis, conversion, orretrieval (i.e., playback), e.g.,

voice recording/playback

ascii-to-fax conversion

facsimile recording/playback

text-to-speech conversion

create conferences.

The number of different services supported by an SCN is very large. Forexample, the SCN may provide an information gateway service in whichuser choices are communicated. As each choice is recognized, thetransfer-with-return procedures executes allowing the user access to thechosen service and to return to the SCN after completing the servicetransaction.

Feature Descriptions:

A) Transfer with Return

This feature allows the SCN (acting as a 2ndStation, in the currentterminology) to call a 1stStation or answer a call from a 1stStation.The SCN may apply a multitude of service circuits to the call (asrequired by a particular service flow), and eventually may transfer thecall to a 3rdStation (possibly an external service module (ESM)). As panof the transfer procedure, the SCN signals that the call should bereturned to the SCN under a variety of conditions.

In addition, if the SCN and the 3rdStations need to communicatecall-related data, the data could be transmitted to the 3rdStationseither as part of the call-setup or could be sent over a RS232 link, aX.25 network, or through the D-channel on ISDN. An alternative would beto transmit the data via a voice channel prior to transferring the1stStation call to the 3rdStation.

B) Return Transfer Triggers

Reconnection to the 2ndStation can be triggered in several ways:disconnection by the 1st or 3rd Station, signaling (e.g., flash or DTMF)by the 1st or 3rdStation. If the feature allows the 1 stStations or3rdStations to signal (e.g., flash or DTMF) reconnection to the2ndStation, then the transfer-with-return feature can work inconjunction with 3-way calling. The 2ndStation may drop out of theconference and then be asked to come back into the conference. In somecases, a 3rdStation may be an ESM, e.g., a mail system. Some of theseESMs may not provide a method by which a caller can request the ESM toinitiate a disconnect. Therefore, to permit the 1stStation to signal areturn to the 2ndStation (the SCN) and disconnect the 3rdStation (theESM) from the call, a call-termination trigger is needed.

C) Call-History on Returned Transfer

As part of the return transfer procedure, the switch alerts the2ndStation (the SCN) with a call set-up message containing the caller'sDN and a transaction₋₋ id (possibly the account code). A reason messageis provided that specifies the reason for the return, e.g., 3rdStationdisconnected, caller-initiated return, etc. The 2ndStation (the SCN) canthen process the call using the appropriate customer logic, anddetermine the call history and billing records from internally storeddata. (Note the call-history capability referred to in Service 1 couldbe provided through an SCN, if all call-transfers return to the SCN, orall call-history records are sent to the SCN).

D) Call-Termination Notification

If the caller disconnects, then a message is sent to the 2ndStation (theSCN), so that the 2ndStation (the SCN) can track service measurementsand 3rdStation usage (if this important for the service).

Service 3: ESM use of Transfer-with-Return feature so that ESM can beinformation & service circuit gateway (FIG. 15)

The features detailed in this service are the same as those specifiedfor Service 1:

transfer-with-return feature

return transfer triggers, in particular a call-termination trigger -call-history feature

call-termination notification

In Service 2, the 2ndStation was operated by a Service Circuit Node. Incontrast, Service 3 uses a simple external service module (gateway-ESM)as the 2ndStation. The gateway-ESM is capable of concurrently answeringmultiple calls (by sending the appropriate control message) andtransferring them to various locations. There is no need for thegateway-ESM to provide announcement circuits or a switch network. The3rdStations that receive the transferred calls can be operated byservice agents or service-circuit ESMs that provide announcements,record/send voice or facsimile, etc. The call flow is shown in FIG. 16.

Feature Description

A) transfer with return

This feature allows the gateway-ESM (acting as a 2ndStation, in thecurrent terminology) to call a 1stStation or answer a call from a1stStation. The ESM can only answer and transfer calls to a 3rdStation(possibly a service-circuit or external service module (ESM)). As partof the transfer procedure, the gateway-ESM signals that the call shouldbe returned to the gateway-ESM under a variety of conditions.

In addition, if the gateway-ESM and the 3rdStations need to communicatecall-related data, the data could be transmitted to the 3rdStationeither as part of the call-setup or could be sent over a RS232 link, aX.25 network, or through the D-channel on ISDN. An alternative would beto transmit the data via a voice channel prior to transferring the1stStation to the 3rdStation.

B) return transfer triggers

Reconnection to the 2ndStation can be triggered in several ways:disconnection by the 1st or 3rd Station, signaling (e.g., flash or DTMF)by the 1st or 3rdStation. If the feature allows the 1stStations or3rdStations to signal (e.g., flash or DTMF) reconnection to the2ndStation, then the transfer-with-return feature can work inconjunction with 3-way calling. The 2ndStation may drop out of theconference and then be asked to come back into the conference. In somecases, a 3rdStation may be an ESM, e.g., a mail system. Some of theseESMs may not provide a method by which a caller can request the ESM toinitiate a disconnect. Therefore, to permit the 1stStation to signal areturn to the 2ndStation and disconnect the 3rdStation (e.g., a voicemail ESM) from the call, a call-termination trigger is needed.

C) call-history on returned transfer

As part of the return transfer procedure, the switch alerts the2ndStation (the gateway-ESM) with a call set-up message containing thecaller's DN and a transaction₋₋ id (possibly the account code). A reasonmessage is provided that specifies the reason for the return, e.g.,3rdStation disconnected, caller-initiated return, etc. The 2ndStation(the gateway-ESM) can then process the call using the appropriatecustomer logic, and determine the call history and billing records frominternally stored data. (Note the call-history capability referred to inService 1 could be provided through a gateway ESM, if all call-transfersreturn to the gateway-ESM, or all call-history records are sent to thegateway-ESM).

D) call-termination notification

If the 1stStation disconnects, then a message is sent to the 2ndStation(gateway-ESM), so that the 2ndStation. (the gateway-ESM) can trackservice measurements and 3rdStation usage (if this important for theservice).

Please note, in this scenario, the human attendant is replaced with anautomated system. This permits several extensions to the basic call flowdescribed earlier:

1. The call could be an in-band or out-of-band data call. This allowsthe concept to support both voice and data applications.

2. Because many automated systems can operate on multiple concurrentcalls, the call flow described previously can be broadened so that thecaller need not be placed on hold during the conversation between theautomated attendant (in this case, a ESM) and the third-party (i.e.,service agent or another ESM). Instead the automated attendant couldmaintain parallel connections with the caller and the third party beforeestablishing a talking path between the caller and third party.

Service 4: Service gateway without switch-based transfer-with-returncapability (FIG. 17)

A networked arrangement of ESMs (or service agents) could havereturn-transfer and call history features without a switch-basedtransfer-with-return capability (switch 20') if each ESM knows about theprimary ESM (the 2ndStation, in the current terminology), and possiblythe other ESMs in the group and each explicitly transferred the callback to the 2ndStation. An exemplary call flow is shown in FIG. 18. Anetwork arrangement of service circuits is provided without modifyingexisting switches. The described features and logic are not restrictedto a network of ESMs, but could be applied equally well to a networkexternal service circuits (ESCs, very similar to an IP, intelligentperipheral) and to a network of telephone users, e.g., a network ofservice attendants and agents of a company.

Feature Descriptions

A) Providing return-transfer capabilities without thetransfer-with-return switch feature

If each service provider (each 2nd and 3rd Station) subscribes tocall-transfer, then a network of service providers can provideservice-circuit based and gateway services without using an SCN andwithout any new switch features. The 2ndStation (a gateway-ESM or aservice attendant) answers the initial call and transfers the call to a3rdStation (a service provider). The directory number of the 2ndStationis passed to the 3rdStation or this information is stored in a databaseon the 3rdStation.

In addition, if the 2ndStation and 3rdStation need to communicateadditional call-related data, the data could be transmitted to the3rdStation either as part of the call-setup (if the amount ofinformation was slight; this may mean enhancing the call-setup infopackage) or over a RS232 link, a X.25 network, or through the D-channelon ISDN. An alternative would be to transmit the data of a voice channelprior to transferring the 1 stStation (the caller) to the 3rdStation.

After the service has been provided by a 3rdStation, the 3rdStationinitiates a call transfer back to the 2ndStation which could thentransfer the call to another service provider (the equivalent of another3rdStation).

B) Providing return-transfer triggers without the return-transfertrigger feature

Each 3rdStation is responsible for transferring the call back to the2ndStation upon request by the 1stStation, or as part of the 3rdStationdisconnect procedure.

C) Providing call-history feature

As part of the transfer procedure, the switch sends additional callhistory information and call instructions back to the call-historysubscriber that initiated the first transfer procedure.

D) Providing call-termination notification withouttermination-notification feature

If the 1stStation (the caller) disconnects, then the 3rdStationreceiving the disconnect signal is responsible for setting up a call tothe 2ndStation with call history information, so that the 2ndStation cantrack service measurements and 3rdStation usage (if this important forthe service).

FIGS. 20-27 provide a state chart model of service 4. FIG. 19 provides asummary of the state transitions.

To improve readability, the following descriptions are partitioned bystate. The notation for each state title should be read as: servicenumber-state number, state name, e.g., 4-1. state Initial, indicatesthat Initial is the name of the first state in the state modeldescribing service 4.

4-1. State Initial (FIG. 20)

The call flow begins in the state Initial, with the initial event,Incoming₋₋ call. This initial event initiates call processing.

The first action taken in this state is to translate the digits dialedby the 1stStation (i.e., the caller) into a specific directory number,and to then initiate a call-setup to the 2ndStation represented by thedialed directory number.

If the call to the 2ndStation is answered (i.e., an event answered isreceived from the 2ndStation), then connect 1st and 2nd Stations andtransition the state model to another state, 2way.

If the event disconnect is received from either station, then the callends.

4-2. State 2way (FIG. 21)

If the event disconnect is received from either station, then the callends.

If the 2ndStation sends an appropriate signal (e.g., a flash or DTMF),and the 2ndStation is a subscriber to the transfer-with-return feature,then the 1stStation is placed on hold, and transition state model toanother state, 2way₋₋ 2ndStationActive.

4-3. State 2way 2ndStationActive (FIG. 22)

The 1stStation (caller) is on hold.

Several events are possible in this state:

event Initial Event

The state begins by processing the internally generated event, Initial₋₋Event. Processing this event results in a tone!collect₋₋ digits actionthat delivers a stuttered tone to the 2ndStation. The stuttered toneprompts the 2ndStation for a feature code, one of which istransfer-with-return, another is transfer-without-return (i.e.,call-transfer as it is currently done).

event collected digits

The digits signaled by the 2ndStation are received as the eventcollected₋₋ digits. If the collected digits indicate a request fortransfer-with-return, a Return₋₋ active indicator is set to true. If thetransfer-with-return or -without-return feature is requested, then asecond tone!collect₋₋ digits action delivers dial tone to the2ndStation. The dial tone prompts the 2ndStation for a directory number.If a valid directory number is received from the 2ndStation, acall-setup procedure is invoked and the state model then transitions toa new state, 3way₋₋ 2ndStationActive₋₋ 3rdStationSetUp

event signal

If the appropriate signal (e.g., a flash) is received by the switch fromthe 2ndStation, the call is returned to the previous 2-way talking pathbetween the 1stStation and 2ndStation, and state model transitions backto the state 2way.

4-4. State 3way 2ndStationActive 3rdStationSetUp (FIG. 23)

The 1stStation is on hold, and the 2ndStation has initiated transferprocedures. Several events are possible in this state:

event call failed

The call could not be connected to the designated directory number,perhaps because the 3rdStation was busy or did not answer. In thisevent, busy or ringing (as appropriate) is delivered to the 2ndStation.The state model then transitions to state 2way₋₋ 2ndStationActive.

event call answered

The 3rdStation answers the call. In this case, the switch establishes a2-way path between the 2nd and 3rd stations. The state model thentransitions to an new state, 3way₋₋ 2ndStationActive₋₋ 3rdStationActive.

event disconnect received from 2ndStation

The 2ndStation disconnects. In this event, the switch establishes a2-way connection between the 1stStation and the 3rdStation. Since the3rdStation has not yet answered, the 1stStation receives audibleringing. The state model then transitions to an new state, 2way₋₋1stStationActive₋₋ 3rdStationActive.

event signal received from 2ndStation

The 2ndStation (the subscriber) signals (typically, but not necessarily,by flashing) a request to return to the 2-way call with the 1stStation.In this event, a talking path is established between the 1st and 2ndstations, and the state model transitions back to the state 2way.

In the next two states, the 2ndStation has a two-way conversation witheither the 1stStation or the 3rdStation. The 2ndStation's signal (flashor DTMF) acts a toggle between these two states. If the 2ndStationsignals a conference request, procedures for a 3-way conversation areinitiated.

4-5. State 3way 2ndStationActive 3rdStationActive (FIG. 24)

In this state the 1stStation is on hold, while the 2nd and 3rd Stationsare connected in a talking path. Two events are significant in thisstate:

event signal for toggle received from 2ndStation

If the 2ndStation signals a single flash (or some DTMF equivalent) thenthe switch opens the path between the 2nd and 3rd Stations, and connectsa path between the 1st and 2nd Stations. The state model thentransitions to a new state 3way₋₋ 1stStationActive₋₋ 2ndStationActive.

event signal for conference received from 2ndStation

If the 2ndStation signals a double-flash (or some DTMF equivalent) thenthe switch creates a 3-way call between the 1st, 2nd, and 3rd Stations.The state model then transitions to a new state 3way.

4-6. State 3way 1stStationActive 2ndStationActive (FIG. 25)

In this state the 3rdStation is on hold, while the 1st and 2nd Stationsare connected in a talking path. Two events are significant in thisstate:

event signal for toggle received from 2ndStation

If the 2ndStation signals a single flash (or some DTMF equivalent) thenthe switch opens the path between the 1st and 2nd Stations, and connectsa path between the 2nd and 3rd Stations. The state model thentransitions back to the state 3way₋₋ 2ndStationActive₋₋3rdStationActive.

event signal for conference received from 2ndStation

If the 2ndStation signals a double-flash (or some DTMF equivalent) thenthe switch creates a 3-way call between the 1st, 2nd, and 3rd Stations.The state model then transitions to a new state 3way.

4-7. State 3way (FIG. 26)

In the 3way state, all three stations are connected together in a 3-wayconference.

If the 2ndStation disconnects, a 2-way call is created between the1stStation and the 3rdStation and the state model transitions to state2way₋₋ 1stStationActive₋₋ 3rdStationActive.

If the 1stStation or 3rdStation disconnects, a 2-way call is createdbetween the two remaining stations (between the 2ndStation and3rdStation, or between the 1stStation and 2ndStation, respectively). If3rdStation disconnects, the state model transitions back to state 2way.If the 1 stStation disconnects, the state model transitions to the state2way, but consider the 3rdStation as if it were the 1stStation (theoriginal 1stStation is no longer pan of the call), except of course, the2ndStation is now the call originator.

4-8. State 2way 1stStationActive 3rdStationActive (FIG. 27)

In this state, the 2ndStation is not part of the call.

Initially, the connection between the 1st and 3rd station is either in aringing state or in a talking state (depending upon whether or not the2ndStation disconnected before or after the 3rdStation answered; or interms of the state model, depending on whether the previous state was3way₋₋ 2ndStationActive₋₋ 3rdStationSetUp or 3way. If either stationdisconnects, the call is terminated, and call-history information isreturned to the 2ndStation.

Note: In Service Concept-4, the 1stStation and 3rdStation cannot recallthe subscriber explicitly by flashing or implicitly by disconnecting. InService Concept-4, the 3rd party must subscribe to the transfer featureand must independently invoke the transfer back to the initial calledparty (the subscriber). In effect, in subsequent processing, the 3rdparty now becomes the call-transfer subscriber.

Four events are significant:

event no answer received from 3rdStation

If the 3rdStation does not answer, the 1stStation continues to hearringing until the 1stStation signals a request to return the call to the2ndStation, or the 1stStation disconnects. No state transition isrequired.

event answer received from 3rdStation

If the 3rdStation answers, then the switch establishes a talking pathbetween the 1stStation and 3rdStation. No state transition is required.

event disconnect received from 1stStation or 3rdStation

The call is terminated and the remaining stations are disconnected.However, if the call-history feature is active then a call historyinformation message is sent to the station that requested call historyinformation.

event signal (flash or DTMF) received from call-transfer subscriber(e.g., 3rdStation)

If the station that signaled is a call-transfer subscriber, then thecall is placed on hold, and the call-transfer subscriber can set up asecond call. The state model transitions to state 2way₋₋SubscriberActive (with an initial event, Initial₋₋ Event).

Service 5: Service gateway without switch-based transfer-with-returncapability and without the call-history feature (FIG. 17)

Service 5 is distinguished from Service 4 by the absence of thecall-history feature in Service 5.

Consider the case in which a caller (a 1stStation) is connected to a2ndStation (e.g., a service attendant or external service module) thathas line subscription to the current practice call transfer feature. The2ndStation transfers the call to a 3rdStation (e.g., a service agent orspecialist, or another external service module). If the 3rdStation alsosubscribes to call transfer, the 3rdStation may at the end of the call,transfer the call back to the same 2ndStation that initially handled thecall (or routed to a co-worker, if the 2ndStation is busy/no-answer).The call flow is shown in FIG. 28. Two assumptions are made that placethis scenario in today's network.

Assumptions:

1. If party A calls Party B, and B transfers the call to Party C, thentwo calls are concurrently active, even though B has disconnected and Ais talking with C. The two calls are the call setup by A, notated hereas (A to B), and the call setup by B, notated here as (B to C). Usingthe terms 1stStation, 2ndStation, and 3rdStation, this means that, inthe current telecommunications environment, (1stStation to 2ndStation)is billed to the 1stStation, and (2ndStation to 3rdStation) is billed tothe 2ndStation. Moreover, the call (1stStation to 2ndStation) does notterminate when the 2ndStation disconnects, but when the 1stStation or3rdStation disconnects.

2. The 3rdStation is provided information about the identity of the2ndStation so that the 3rdStation can redirect the call back to the2ndStation.

The description of the service concept is structured into two scenarios:

In Scenario A, the 3rdStation terminates the transaction with the1stStation;

In Scenario B, the 3rdStation transfers the call back to the 2ndStation

Each scenario is further partitioned into two services:

the Bill Correlation Service, in which the separate billing records thatare generated by each call (the initial call and each subsequentcall-transfer) are correlated and combined into a single billing record.

the Bill Discounting Service, in which particular bills are discountedbased upon their association with well-defined criteria (e.g.,call-transfers originating from a 2ndStation).

Scenario A (FIG. 29)

1. 1stStation dials 2ndStation (or hunt group that terminates to2ndStation)

2. 2ndStation answers; 1st and 2ndStation talk

3. 2ndStation places call to 3rdStation (if the 2ndStation is a person,this may require first placing the 1stStation on hold)

4. 3rdStation answers; 2ndStation and 3rdStation talk

5. 2ndStation creates 3-way call involving 1stStation, 2ndStation, and3rdStation

6. 2ndStation disconnects; 1st and 3rd Station talk

7. 1st or 3rd Station disconnect

Billing Records:

The billing records created for this scenario are:

a. (1st to 2nd Stations) for network resource usage spanning events (2)through (7)

b. (2nd to 3rd Stations) for network resource usage spanning events (4)through (7)

Assume that all billing records are accessible to the same billingcenter (or interconnected network of billing centers) for furtheranalysis, and that both types of billing records are applied to the2ndStation account (as in reverse-charged calls or free phone calls,e.g., 800 calls).

There are two billing and measurement service sets that are provided asan illustration of how new billing and measurement services could berealized using current (or slightly modified) transfer capabilities.These services are applied to the billing records created for each callin the Scenario A call flow. After a discussion of these services in thecontext of the Scenario A call flow, the same services will beconsidered in another call flow context, Scenario B. In Scenario B, thetransferred-to party, i.e., the 3rdStation, transfers the call back tothe initial transferring party, the 2ndStation.

Service Set-5.1, Bill Correlation Service:

Using Scenario A, the Bill Correlation Service provides measurements ontransfer operations and provides discount billing services.

Assume that each bill contains:

calling and Terminating DNs,

the time at which the call is answered--referred to as Origination Time,

the time at which the call is ended--referred to as Termination Time,

a call-transfer indication flag that the call involved a call transfer,e.g., in the scenario call (2nd to 3rdStation) involved a call transferor indicating a call identification.

the time at which the Terminating party disconnects--referred to as theDisconnect Time (the service provider disconnect time). Note, if thisstatistic is not provided in the billing record, the basic conceptdescribed herein is not seriously impacted. It merely means that certaincalculations are not performed. In particular, the overlap time referredto herein is not calculated. The overlap time is the duration duringwhich the 2ndStation is conducting two 2-way conversations (and flashingto alternate between talking with the 1stStation and the 3rdStation), orone 3-way conversation.

Bill and Measurements Calculation Method for Service Set-5.1A

1. Search billing records for all calls in which the call-transferindication is set to true. Such billing records will be referred to as aTransfer-Bills. All other bills are categorized as non-Transfer-Bills.In the present scenario, (1st to 2nd Station) is a non-Transfer-Bill,and (2nd to 3rd Station) is a Transfer-Bill

2. For each non-Transfer-Bill terminating to a subscriber, search theTransfer-Bills for the Transfer-Bill in which:

the subscriber DN is equal to the originating DN of the Transfer-Bill,and

the originating time and termination time of the call is subsumed by theoriginating and terminating times of the call described by thenon-Transfer Bill.

Note: the call-transfer indication flag is not essential, it merelyreduces the search time for identifying Transfer- andnon-Transfer-Bills. Another method is to:

1. locate all bills originating from or terminating to subscribers;

2a. for each bill for a call originating from a subscriber find a bill(if any) in which

the call terminates to that subscriber, and

the origination and termination times subsumes the origination andtermination times of the bill originating from the subscriber

2b. for each located pair of bills, the bill for the call originatingfrom the subscriber is a Transfer-Bill, and the call terminating to thesubscriber is a non-Transfer-Bill.

3. Create a composite call history with the following information: Theformat of the following calculations is relation (Billing record), whererelation describes a type of information contained in the Billingrecord, and relation (Billing record) is the value of that information.For example, caller DN (1stStation to 2ndStation) is the directorynumber of the caller; and Origination Time (1 stStation to 2ndStation)is the time at which the call to 2ndStation was answered. The symbols -and + have their standard arithmetic interpretations. The symbol=may beinterpreted as is equal to.

a. Subscriber: caller DN (1st to 2nd Station)

b. Total Duration=Termination Time (1st to 2nd Station)--OriginationTime (1st to 2nd Station)

c. Calling Party=caller DN (1st to 2nd Station)

d. Transferring Party=Terminating DN (1st to 2nd Station)=caller DN (2ndto 3rd Station)

e. Transferred-to Party=Terminating DN (2nd to 3rd Station)

f. Call Segment 1: Calling Party and Transferring Party

g. Segment 1 origination time=Origination Time (1st to 2nd Station)

h. Segment 1 duration=Origination Time (2nd to 3rd Station)--OriginationTime (1st to 2nd Station)

i. Call Segment 2: Calling Party and Transferred-to Party

j. Segment 2 origination time=Origination Time (2nd to 3rd Station)

k. Segment 2 duration=Termination Time (1st to 2nd Station)--OriginationTime (2nd to 3rd Station)

l. Calling Party call duration=Total Duration=Segment1 duration+Segment2duration

m. Transferring Party call duration=Disconnect Time (1st to 2nd Station)Origination Time (1st to 2nd Station)

n. Transferred-To Party call duration=Segment 2 duration

o. Overlap (two concurrent 2-way calls, and/or one 3-way call involvingcaller, transferring, and transferred-to parties): Disconnect Time (1 stto 2nd Station)--Origination Time (2nd & 3rd Station)

The calculations can be visualized as shown in FIG. 30. Refer to Table1.

                  TABLE 1                                                         ______________________________________                                        Segment 1:           originating time = F.sub.0                                                    terminating time = T.sub.0                               Segment 2:           originating time = T.sub.0                                                    terminating time = T.sub.t                               Overlap between Segments 1 and 2 = S.sub.d -T.sub.0                           Caller Total Duration: F.sub.t -F.sub.0                                       2ndStation actual Duration: (S.sub.d -S.sub.0)                                3rdStation actual Duration: (T.sub.t -T.sub.0)                                current practice, Bill 1: F.sub.t -F.sub.0 (originator of call:               1stStation)                                                                   current practice, Bill 2: T.sub.t -T.sub.0 (originator of call:               2ndStation)                                                                   ______________________________________                                    

4. Use composite call history to derive billing charges

For example, certain subscribers (identified by the originating dn of aTransfer-Bill) who often act as transferring parties may subscribe tobilling plans that calculate charges based only on the Calling Partycall duration.

Other billing plans for usage charges are also possible, e.g., (CallingParty call duration+Overlap) which would more accurately reflect thenumber of logical calls in the system and would charge for the amount oftime the transferring party is talking to both the caller and thetransferred-to party.

A variety of measurements may be derived from the composite callhistory, especially if the transferred-to parties can be grouped byspecialty. For example:

(a.) Number of calls to a particular attendant which are subsequentlytransferred

(b.) Number of calls to a particular attendant which are subsequentlytransferred, broken down by the number of calls transferred-to each setof specialists.

(c.) Number of calls transferred to a particular set of specialists

(d.) Average length of overlap per attendant (transferring party)

(e.) Number of calls from a particular geographic region to a particularspeciality (i.e., a group of specialists)

Measurement (a) indicates how many calls required additional help from aspecialist. Assuming calls are randomly distributed to attendants,Measurement (b) may identify attendants who transfer calls too quicklyor who need additional training in particular areas. Measurement (c)could be used to indicate what areas of specialty are frequently beyondthe expertise of attendants. This might be used to identify additionaleducational needs for the attendant community. Measurement (d) indicatesthe average time needed by an attendant to introduce the caller to aspecialist. Attendants with relatively small or large values ofmeasurement (d) may identify attendants with poor communication skills.Outlier values of Measurement (e) might indicate a regional problem inservicing a product, distributing new releases of a product, or regionalmanufacturing of a product.

Service Set-5.2A, Bill Discounting Service

Using Scenario A, the following is a Bill discounting service that billsfor only the call duration used by the caller.

Assume that each billing record contains:

calling and Terminating DNs,

the time at which the call is answered--referred to as Origination Time,

the time at which the call is ended--referred to as Termination Time,

a call-transfer indication flag that indicates that the call involved acall transfer, e.g., the call (2nd to 3rd Station) involved a calltransfer.

1. Search billing records for all calls in which the call-transferindication is set to true. Such billing records will be referred to as aTransfer-Bills. All other bills are categorized as non-Transfer-Bills.In the present scenario, (1 st to 2nd Station) is a non-Transfer-Bill,and (2nd to 3rd Station) is a Transfer-Bill.

2. If the originating dn of a billing record matches a list of preferredsubscribers, then discount entire amount of usage charge on that bill.This effectively means that a business customer pays only for usagederived from calls originated by the caller, and not for the internalredirecting of calls from one service provider (attendant or agent orESM) or another.

Scenario B (FIG. 31)

1. 1stStation calls 2ndStation (or hunt group that terminates to2ndStation)

2. 2ndStation answers; 1stStation and 2ndStation talk

3. 2ndStation places call to 3rdStation (if the 2ndStation is a person,this may require first placing the 1stStation on hold)

4. 3rdStation answers; 3rdStation and 2ndStation talk

5. 2ndStation creates 3-way call involving 2ndStation, 3rdStation, and1stStation

6. 2ndStation disconnect; 3rdStation and 1stStation talk

7. 3rdStation places call to 2ndStation (if the 3rdStation is a person,this may require first placing the 1stStation on hold)

8. 2ndStation answers; 3rdStation and 2ndStation talk

9. 3rdStation creates 3-way call involving 2ndStation, 3rdStation, and1stStation

10. 3rdStation disconnect; 2ndStation and 1stStation talk

11.2ndStation and 1stStation disconnect

The billing records created for this scenario are:

a. (1st to 2nd Station) for network resource usage spanning events (2)through (11)

b. (2nd to 3rd Station) for network resource usage spanning events (4)through (11)

c. (3rd Station to 2nd Station) for network resource usage spanningevents (7) through (11)

Assume that all billing records are accessible to the same billingcenter for further analysis, and that all three types of bills areapplied to the 2ndStations account (as in reverse-charged calls or freephone calls, e.g., 800 calls).

Service Set-5.1B: Bill Correlation Service

Using Scenario B, the Bill Correlation Service provides measurements ontransfer operations and provides discount billing services.

Assume that each bill contains:

calling and Terminating DNs,

the time at which the call is answered--referred to as Origination Time,

the time at which the call is ended--referred to as Termination Time,

a call-transfer indication flag that the call involved a call transfer,e.g., in the scenario call (2nd to 3rd Station) involved a calltransfer.

the time at which the Terminating party disconnects--referred to as theService Provider Disconnect Time

Assume that 2ndStation and 3rdStation are subscribers to thecurrent-practice call-transfer feature and to the Bill CorrelationService.

1. Search billing records for all calls involving at least onesubscriber. The resulting set is referred to as the Subscriber set.

2. Search the subscriber set for all calls in which the call-transferindication is set to true. Such billing records will be referred to as aTransfer-Bills. All other bills are categorized as non-Transfer-Bills.In the present scenario, (1st to 2nd Station) is a non-Transfer-Bill,and (2ndStation to 3rdStation) is a Transfer-Bill.

3. For each non-Transfer-Bill terminating to a subscriber, search theTransfer-Bills for any Transfer-Bill in which:

the subscriber DN of the non-Transfer-Bill is equal to the originatingor terminating DN of the Transfer-Bill, and

the originating time and termination time of the call described in theTransfer Bill is subsumed by the originating and terminating times ofthe call described by the non-Transfer Bill.

Step (3) creates a set of bills containing a non-Transfer-Bill and zero,one, or many Transfer Bills.

4. Create a composite call history with the following information: Theformat of the following calculations is relation (Billing record), whererelation describes a type of information contained in the Billingrecord, and relation (Billing record) is the value of that information.

For example, caller DN (1stStation to 2ndStation) is the directorynumber of the caller; and Origination Time (1stStation to 2ndStation) isthe time at which the call to 2ndStation was answered. The symbols -and + have their standard arithmetic interpretations. The symbol=may beinterpreted as is equal to.

a. Subscriber: caller DN (2nd to 3rd Station)

b. Total Duration=Termination Time (1st to 2nd Station)--OriginationTime (1st to 2nd Station)

c. Calling Party=caller DN (1st to 2nd Station)

d. 1stTransferring Party=Terminating DN (1st to 2nd Station)

e. 1stTransferred-to Party=Terminating DN (2nd to 3rd Station)

f. 2ndTransferring Party=Originating DN (3rd to 2nd Station)

g. 2ndTransferred-to Party=Terminating DN (3rd to 2nd Station)

h. Call Segment 1: Calling Party and Transferring Party

i. Segment 1 origination time=Origination Time (1st to 2nd Station)

j. Segment 1 duration=Origination Time (2nd to 3rd Station)--OriginationTime (1st to 2nd Station)

k. Call Segment 2: Calling Party and Transferred-to Party

l. Segment 2 origination time=Origination Time (2nd to 3rd Station)

m. Segment 2 duration=Origination Time (3rd to 2nd Station)--OriginationTime (2nd to 3rd Station)

n. Call Segment 3: Calling Party and initial Transferring Party

o. Segment 3 origination time--Origination Time (3rd to 2nd Station)

p. Segment 3 duration=Termination Time (1st to 2nd Station)--OriginationTime (3rd to 2nd Station)

q. Calling Party call duration=Total Duration==Segment1duration+Segment2 duration+Segment3 duration

r. 2ndStation call duration--[Disconnect Time (1st to 2ndStation)--Origination Time (1st to 2nd Station)]+[Termination Time (3rdto 2nd Station)--Origination Time (3rd to 2nd Station)]

s. 3rdStation call duration=Disconnect Time (3rd to2ndStation)--Origination Time (2nd to 3rd Station)

t. Overlap between segments 1 and 2 (two 2-way calls, and/or 3 way callinvolving caller, transferring, and transferred-to parties): DisconnectTime (1st to 2ndStation)--Origination Time (2nd to 3rd Station)

u. Overlap between segments 2 and 3 (two 2-way calls, and/or 3 way callinvolving 1st, 2nd, and 3rd Stations): Disconnect Time (2nd to 3rdStation) Origination Time (3rd to 2ndStation)

The calculations can be visualized as shown in FIG. 32. Refer to Table2.

                  TABLE 2                                                         ______________________________________                                        Segment 1:        originating time = F.sub.0                                                    terminating time = T.sub.0                                  Segment 2:        originating time = T.sub.0                                                    terminating time = S'.sub.0                                 Segment 3:        originating time = S'.sub.0                                                   terminating time = S'.sub.t or F.sub.t                      Overlap between Segments 1 and 2 = S.sub.d -T.sub.0                           Overlap between Segments 2 and 3 = T.sub.d -S'.sub.0                          Caller Total Duration: F.sub.t -F.sub.0                                       2ndStation actual duration: (S.sub.d -S.sub.0) + (S'.sub.t -S'.sub.0)         3rdStation actual duration: (T.sub.d -T.sub.0)                                current practice, Bill 1: F.sub.t -F.sub.0 (originator of call:               1ststation)                                                                   current practice, Bill 2: F.sub.t -T.sub.0 (originator of call:               2ndStation)                                                                   current practice, Bill 3: F.sub.t -S'.sub.0 (originator of call:              3rdStation)                                                                   ______________________________________                                    

Service Set-5.2B Bill Discounting Service

Using Scenario B, the following describes a Bill Discounting Servicethat bills for only the call duration used by the caller.

Assume that each billing record contains:

calling and Terminating DNs,

the time at which the call is answered--referred to as Origination Time,

the time at which the call is ended--referred to as Termination Time,

a call-transfer indication flag that indicates that the call involved acall transfer, e.g., in the scenario (2nd to 3rd Station) involved acall transfer.

1. Search billing records for all calls in which the call-transferindication is set to true. Such billing records will be referred to as aTransfer-Bills. All other bills are categorized as non-Transfer-Bills.In the present scenario, (1st to 2nd Station) is a non-Transfer-Bill,and (2nd to 3rd Station) and (2nd to 3rd Station) are Transfer-Bills.

2. If the originating dn of a Transfer Bill billing record matches a DNon a list of preferred subscribers, then discount entire amount of usagecharge on that bill. This effectively means that a business customerpays only for usage derived from calls originated by the caller, and notfor the internal redirecting of calls from one service provider(attendant or agent or ESM) to another.

Note: the call-transfer indication flag is not essential, it merelyreduces the search time for identifying Transfer- andnon-Transfer-Bills. Another method is to:

1. locate all bills originating from or terminating to subscribers;

2a. for each bill for a call originating from a subscriber find a bill(if any) in which--the call terminates to that subscriber, and--theorigination and termination times subsumes the origination andtermination times of the bill originating from the subscriber

2b. for each located pair of bills, the bill for the call originatingfrom the subscriber is a Transfer-Bill, and the call terminating to thesubscriber is a non-Transfer-Bill.

Description of Prior Art Billing Service (FIG. 33)

Call transfer in a centrex or ISDN environment allows subscribers toreceive or originate a call, receive or originate a second callconcurrent with the first call, join the two calls together into a 3-waycall, and disconnect from the call while allowing the other two partiesto continue talking. A state diagram and call flow are shown in FIGS. 34and 35.

Terminology

The following scenario will consider call-transfer from the perspectiveof a 2ndStation that receives a call from a 1stStation, and transfersthat call to a 3rdStation, yielding a conversation between the1stStation and the 3rdStation (the 2ndStation has disconnected). Instandard telecommunications terminology the 1stStation is frequentlycalled the calling party, the 2ndStation is typically referred to as thetransferring party, and the 3rdStation is often called thetransferred-to party.

Network Routing

In current practice, a transferred call is routed from the switchingoffice of the 1stStation (termed the 1stSwitch) to the 2ndSwitch to the3rdSwitch, even after the 2ndStation has disconnected.

Billing Practices

In current practice, the originating switch of the first call produces abill that is handled independently from the bill generated by theoriginating switch of the second call (even if the same switch isinvolved for both call originations).

Each originated call generates a billing record.: the call from the1stStation to the 2ndStation; the call from the 2ndStation to the3rdStation. Both calls terminate when the 1stStation or 3rdStationdisconnect. The billing practice does not reflect the time at which the2ndStation disconnects.

If the 3rdStation were to initiate a 3rd call (a second transfer) whiletalking with the 1stStation, then a third bill would be created for thecall from the 3rdStation to the 4thStation (the 4thStation may beequivalent to the 2ndStation if the 3rdStation transfers the call backto the 2ndStation). In this case, all three bills would depend upon thedisconnect time of the 1st or 4thStation (and would not reflect thedisconnect times of the 2nd or 3rdStations). Event diagrams for ScenarioA are shown in FIGS. 36 and 37. An event diagram for Scenario B is shownin FIG. 38. Refer to Table 3 for Scenario A and Table 4 for Scenario B.

                  TABLE 3                                                         ______________________________________                                        Segment 1:           originating time = A.sub.0                                                    terminating time = C.sub.0                               Segment 2:           originating time = C.sub.0                                                    terminating time = C.sub.1                               Billing Practice:                                                             current practice, Bill 1: A.sub.t -A.sub.0                                    (originator of call: 1stStation)                                              bill based on tariff for 1stStation to 2ndStation calls;                      bill generated by 1stSwitching office;                                        bill produced when 1stStation or 3rdStation disconnect                        current practice, Bill 2: C.sub.t -C.sub.0                                    (originator of call: 2ndStation)                                              bill based on tariff for 2ndStation to 3rdStation calls;                      bill generated by 2ndSwitching office;                                        bill produced when 1ststation or 3rdStation disconnect                        No bill created based on 1stStation to 3rdStation distance.                   Bill for second call not dependent upon 2ndStation disconnect.                ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Segment 1:         originating time=A.sub.0                                                      terminating time=C.sub.0                                   Segment 2:         originating time=C.sub.0                                                      terminating time=B'.sub.0                                  Segment 3:         originating time=B'.sub.0                                                     terminating time=B'.sub.t or A.sub.t                       Overlap between Segments 1 and 2 = B.sub.d -C.sub.0                           Overlap between Segments 2 and 3 = C.sub.d -B'.sub.0                          Caller Total Duration: A.sub.t -A.sub.0                                       2ndStation actual duration: (B.sub.d -B.sub.0) + (B'.sub.t -B'.sub.0)         3rdStation actual duration: (C.sub.d -C.sub.0)                                current practice, Bill 1: A.sub.t -A.sub.0 (originator of call:               1stStation)                                                                   current practice, Bill 2: A.sub.t -C.sub.0 (originator of call:               2ndStation)                                                                   current practice, Bill 3: A.sub.t -B'.sub.0 (originator of call:              3rdStation)                                                                   ______________________________________                                    

A further alternative method used in the arrangement of FIG. 40 includesconnecting a call from a first station to a second station.Contemporaneously with connecting the call to the second station, thetransmission of first call segment event messages is initiated to abilling center, e.g., a nationwide billing center. The call is thenconnected to a third station. Contemporaneously with connecting the callto the third station, the transmission of second call segment eventmessages is iniatiated to the same billing center. After all of thefirst and second call segment event messages have been transmitted, thebilling center correlates them to generate a single billing record foruse in billing the call.

It is to be understood that the above-described embodiments are merelyillustrative of the principles of the invention and that many variationsmay be devised by those skilled in the art without departing from thespirit and scope of the invention. It is therefore intended that suchvariations be included within the scope of the claims.

I claim:
 1. A call processing and billing method comprising connecting acall from a first station to a second station,contemporaneously withsaid connecting of said call to said second station, initiating a firstbilling record for said call, connecting said call to a third station,contemporaneously with said connecting of said call to said thirdstation, initiating a second billing record for said call, completingsaid first and second billing records proximate to the end of said call,said first billing record reflecting a first time duration and saidsecond billing record reflecting a second time duration, delivering saidfirst and second billing records to a common billing center, correlatingsaid first and second billing records to generate a single billingrecord such that said single billing record reflects a resultant timeduration different from the sum of said first and second time durations,and establishing a charge for said call dependent on said resultant timeduration.
 2. A method in accordance with claim 1 where said connectingof said call to said third station comprisesconferencing said thirdstation into said call.
 3. A method in accordance with claim 1 wheresaid connecting of said call to said third station comprisestransferringsaid call to said third station.
 4. A method in accordance with claim 3where said transferring of said call to said third stationcomprisesconnecting one of said first and second stations with saidthird station for an initial two-way consultation and thereafterconnecting the other of said first and second stations with said thirdstation for two-way consultation.
 5. A method in accordance with claim 3where said transferring of said call to said third stationincludesinitially connecting said first, second and third stations for aconference.
 6. A method in accordance with claim 3 where saidtransferring of said call to said third station compriseswithout havingpreviously connected one of said first and second stations with saidthird station for an initial two-way consultation, connecting the otherof said first and second stations with said third station for two-wayconsultation.
 7. A method in accordance with claim 1 where saidcorrelating comprisesmodifying one of said first and second billingrecords using information from the other of said first and secondbilling records to generate said single billing record.
 8. A method inaccordance with claim 1 where said correlating comprisescombininginformation from said first and second billing records to generate saidsingle billing record.
 9. A method in accordance with claim 1 where saidcorrelating comprisesusing information from only one of said first andsecond billing records to generate said single billing record.
 10. Amethod in accordance with claim 9 where only one of said first andsecond billing records is used as said single billing record.
 11. Amethod in accordance with claim 1 further comprisingincluding anidentifier, in at least one of said first and second billing records,for use in said correlating.
 12. A method in accordance with claim 1further comprisingconnecting said call to a fourth station, andcontemporaneously with said connecting of said call to said fourthstation, initiating a third billing record for said call, where saidcorrelating comprises correlating said first, second and third billingrecords to generate said single billing record.
 13. A method inaccordance with claim 1 wherein delivering said first and second billingrecords includes transmittingcall segment event messages to said commonbilling center said common billing center utilizing said call segmentevent messages to generate said single billing record.
 14. A method inaccordance with claim 1 further comprisingsubsequent to connecting saidcall to a said third station, disconnecting said first station from saidcall, transferring said call back to said first station,contemporaneously with said transferring of said call back to said firststation, initiating a third billing record for said call, and where saidcorrelating includes correlating said first, second and third billingrecords to generate said single billing record for use in billing saidcall.
 15. A method in accordance with claim 14 where said transferringof said call back to said first station comprisesautomatically returningsaid call to said one station in response to a prespecified eventwithout receiving a dialed number for said one station.
 16. A method inaccordance with claim 15 where said prespecified event is receivingdisconnect signaling from only one of said other and third stations. 17.A method in accordance with claim 15 where said prespecified event isreceiving predefined signaling from one of said other and thirdstations.